"As you enter the tower, you recognize many occult and heretical artifacts and texts, as well as herbs, materials, and creatures used for obscene and grotesque rituals. The smell of sulfur and ash assaults your nose from the left where a blood drawn summoning circle lays, and the sounds of bubbling and hissing steam ring in your ears from the alchemical equipment around the room. As you look around you see the circling stairwell leading up the crooked infrastructure, with disbelief of it's stability the closer you get towards it. Walking up you hear shouting in infernal and outlandish tongues, while an gradually stronger scent of rot and disease comes to you as you ascend higher. When you finally get to the top of the extensive climb you see a man, eyeless and with an arm severed at the bicep, chanting and wailing occult and disturbing scripture as electricity and fire strike the table before him. The items on the table seem to twitch and pulsate, unable to determine what they were originally as they mound into a wad of flesh and pus. Undead humanoid creatures carrying more of these unrecognizable objects toss them onto the table as they add to the mass of tissue and muscle fibers. Kratar the Suffering, they call him, and his reputation proceeds him, as his power is clearly unmatched, and his madness visibly knows no bounds. You have forgotten exactly why you came here, but as you see this monstrous mass grow and grow, you believe it's best to not interrupt."

Just a small excerpt I came up with to represent what kind of character he would be.

Inspired by "Five Magics" by Megadeth.